Westbourne specialises in providing financial advice to business people in eastern Europe, Russia and other parts of the world.
In the past few months Kevin Maxwell, who is Britain's biggest bankrupt, has flown regularly on business.
He is said to earn less than £20,000 a year before expenses, not enough to make any payments to his creditors, who are owed more than £400m.
Lawyers at Peters and Peters, the firm acting for the Maxwell brothers, said that the £4m spent in legal fees represented the approximate figure paid to solicitors, barristers and accountants instructed on behalf of six separate defendants, including theMaxwell brothers.
A prepared statement by Peters and Peters says that they regarded further comment as inappropriate given that preparatory hearings were already being held by a judge and a jury for the fraud case was due to be chosen in nine weeks' time.
As eligibility for legal aid becomes tighter for the majority of applicants, there has been growing concern about the sums of legal aid spent on high-profile cases centring on people who appear to live relatively affluent lives, often made possible by the support of their families and friends.
Kevin Maxwell now lives with his wife, Pandora, and the couple's five children in a converted barn near Pangbourne in Berkshire.
It is a property, said to be worth about £300,000, that was bought for the family by his father-in-law, John Warnford-Davies.
In May last year, the Sunday Times described the home, which also houses Kevin's parents-in-law, as a "house fit for a millionaire".
The three Maxwell children of school age, who used to attend a private school with fees of £6,000 a year, are now said to attend a local state school.
Friends of the family helped to pay for the children's education for a limited period, but a decision to move them was taken at the end of the last school year.
"Kevin felt that it was inappropriate to continue to educate them privately given his circumstances, although he was more than grateful for his friends' support,'' a source said yesterday.
Under his bail conditions Kevin Maxwell's lawyer at Peters and Peters has to call the Serious Fraud Office to inform officials whenever he leaves the country.
As a bankrupt he has a trustee in bankruptcy, who is sent a monthly statement of his income and expenditure.
Under bankruptcy rules he could be automatically discharged as a bankrupt later this year - three years after he was made bankrupt - unless he is found to have not declared his income properly.
Ian Maxwell, who staved off bankruptcy, is said to live in London with his wife, Laura Plumb, who has been working with an independent company organising finance for British films.
The brothers' mother, Elisabeth, widow of the publisher Robert Maxwell, has just had her autobiography published by Macmillan. She spends most of her time in France.
Yesterday, friends at Westbourne's offices on the second floor of a town house in Mayfair, central London, said that the two Maxwell brothers were spending an increasing amount of their time on the defence for their trial, which is set to begin in April - nearly three years after the brothers were first arrested.
In the past lawyers have voiced their concern about apparently wealthy people being eligible for legal aid when the poorest applicants are finding increasing difficulty in qualifying for the scheme.
Denise Kingsmill, a lawyer at Denton Hall, which operates a substantial white-collar crime unit, said that the rules could be changed to allow family and friends to contribute to a defendant's legal bills.
But she warned that this could represent the "thin end of a wedge" which might result in families and friends being obliged to make such a contribution.
"The real problem about legal aid is that fewer and fewer people qualify for it because of the stricter limits even though there is a much greater need for legal aid these days because life has become a lot more legalistic," she said.
"These Serious Fraud Office cases are very complicated and so long as it is decided to run cases in this way, somebody is going to have to pay for them. After all, these people are innocent until proven guilty."Reuse content